The U.S. government is aggressively pursuing intelligence that Saddam Hussein may have sent operatives to the United States, ABCNEWS has learned.

"We should fully expect that he would use whatever capability he has to inflict harm on us or our allies, and … certainly us at home if he can do it," said ABCNEWS consultant Robert Gallucci, the dean of the Georgetown University School of Foreign Service.

Sources told ABCNEWS that the possibility of Iraqi infiltrators is one reason why the FBI has launched a massive campaign to interview 50,000 Iraqi-Americans and Iraqis living in the United States. Of particular interest are scores of Iraqis ordered by immigration judges to leave the country — but who may have disappeared.

Also spurring government concern are two events.

The FBI dispatched agents to Jamaica to interview 10 men of Iraqi descent who were thought to be headed to the United States.

And today officials in the Philippines announced the expulsion of an Iraqi diplomat to Manilla, Husham Husain, accusing him of participating in a bombing that left one U.S. soldier and three Filipinos dead last October.

"I requested that Mr. Husain leave the country in 48 hours," said Blas Ople, the Philippines' foreign affairs secretary.

The combination of threats from al Qaeda and the possibility of a domestic threat from Iraqi infiltrators is stretching law enforcement to its limit.

"It's not only looking for possible Iraqi plants or Iraqi supporters here but certainly al Qaeda supporters," said Harry "Skip" Brandon, former deputy assistant director of the FBI for counterterrorism and counterintelligence. "Then if we go to war or get close to it, people who simply … feel like Islam is being attacked, even on their own may undertake suicides missions or something like this."